DESCRIPTION (adapted from the application) This application requests support for the 18th Gordon Conference on the Chemistry and Biology of Tetrapyrroles, to be held at Salve Regina University, Newport, Rhode Island, from July 16-21, 2000. This biennial interdisciplinary conference has a record of over more than three decades of stimulating collaborations between basic biologists, chemists, biochemists, and clinicians interested in tetrapyrroles. In association with proteins, tetrapyrroles serve diverse roles as biological redox catalysts, in the harvesting of light energy, in oxygen activation and delivery, and in signaling systems. Free tetrapyrroles are essential nutrients (i.e., vitamin B12), serve as regulators of gene expression (i.e., heme), and are utilized as therapeutic agents (e.g., photodynamic cancer therapy, targeted delivery of radionuclides). Owing to their lipophilicity, photodynamic activity, and redox toxicity, the accumulation of tetrapyrroles (e.g. porphyrins, bilirubin, heme) is associated with numerous pathologies of the skin, liver and brain. For these reasons, this conference represents an important venue for the exchange of information between basic and applied researchers in the tetrapyrrole area and for the refinement of new tools and therapies by the biomedical community. The funds requested in this application are intended to support the participation of 6 young investigators and/or women who have not previously attended the conference. Sessions have been specifically included in the program to showcase the advances made by these investigators. There will be 20 invited speakers, a plenary lecturer, and 9 discussion leaders, who have been selected for their scientific excellence, innovative work, and contribution to the breadth of the program. An afternoon workshop on clinical aspects of porphyrin metabolism with 8 short talks and 2 discussion leaders is also planned. The remaining 100 conferees will be chosen to ensure a strong representation of women, young scientists, and a diversity of ethnic and geographical backgrounds. Participants will be drawn from academic institutions, medical research laboratories, and industry. The strengths of this ongoing Gordon Conference are its extraordinary disciplinary diversity, integration of research from basic chemistry through actual clinical applications, focus on new unpublished work, extended discussion time, informal atmosphere, and ban on dissemination of conference proceedings.